Elasticsearch does not update automatically

Summary

Like https://gitlab.com/gitlab-org/gitlab-ee/issues/355

Steps to reproduce

• We use Gitlab 9.5.5-ee. Backup all data (near 17G).
• Install Gitlab 9.5.5-ee and restore backup and gitlab.rb in a new server.
• Input Elasticsearch URL and uncheck Elasticsearch indexing and Search with Elasticsearch enabled
• Follow https://docs.gitlab.com/ee/integration/elasticsearch.html#adding-gitlab-39-s-data-to-the-elasticsearch-index Add GitLab's data to the Elasticsearch index, two methods are all tried.
• Turn on Elasticsearch indexing and Search with Elasticsearch enabled.
• Searching with Elasticsearch is worked.
• Push new code to any repos.
• New code is not shown in search.
• do gitlab-rake gitlab:elastic:index_repositories, works.

What is the current bug behavior?

elastic_indexer or any other jobs not run.

Relevant logs and/or screenshots

There is not any related logs in /var/log/gitlab/gitlab-rails/sidekiq.log.

New file push to a repo.

Not shown in search results.

Old file in search results.

Sidekiq status.